NPC cacti/nagios

Hello,
I compiled cacti 0.8.7g and installed nagios on ubuntu server 12.04 using:

apt-get install nagios3

I can't find the configuration files I need to edit to define hosts, services etc.
I'm trying to use npc to integrate with cacti but it shows nagios status as off.
Do I have to compile nagios to get it to work or where can I find these .cfg files.
Thank you.

Adeyinca


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